Starting bit for rotary masonry bits



March so, 1954 w, M BACQN 2,673,717

STARTING BIT FOR ROTARY MASONRY BITS Filed March 14, 1951 1? y f2 77 46 r j willi IN V EN TOR. Mmes/v M 54cm/ @amc/.My

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Patented Mar. 30, 1954 STARTING BIT FOR IOTARY MASONRY BIT Warren M. Bacon, Cleveland Heights, Ohio, as-

signor of one-half to Oliver P. Link, Cleveland,

Application March 14, 1951, Serial No. 215,594

(Cl. Z55-69) Claims.

This invention relates generally to rotary bits, and more particularly, to a starting bit or tool, adapted to initiate a piercing or cutting operation in such hard granular structures such as concrete, brick and the like. More specifically, my invention is adapted to be attached to and used with, masonry drill bits of the type having a cylindrical body with a disc shaped head of concentric, external circumference, xed on the operating end of the body, and provided withv cutting members or teeth positioned radially on the face of the head perpendicular to the axis of rotation, While screw threads on the exterior of the body function to remove material cuttings from the hole being drilled. The type of bit above referred to is illustrated in United States Letters Patent No. 2,506,474, issued to Carl V. Tilden on May 2, 1950.

In using the above type of rotary bit to pierce a masonry wall, the initial opening in the Wall before using the drill, in conventional practice, is made by a hand chipping tool, which is a time consuming operation, furthermore it is diflicult to accurately center the initial opening at the desired part by this means and such operation frequently results in fracturing or splitting the masonry adjacent thereto. I have discovered that the initial piercing operation can be accomplished by providing a pointed removable starting tool adapted to be readily connected to and detached from, a rotary bit with the rear of the cutting head locking with the cutting members disposed on the head of the drill.

An object of the invention is to provide a removable starting tool to initiate a piercing operation for a masonry drilling operation, which can be quickly and easily attached to and detached from a conventional drill without altering the same.

Another object is to provide a starting tool which can start a hole at the exact point desired without chipping the sides thereof.

Other objects are to provide a durable, low cost starting drill, which can be easily sharpened, is adapted to initiate masoniy piercing operations for a relatively wide range of hole cliarneters, and is adapted to be operated in various positions.

These and other objects will appear in the course of the following illustrative embodiment of the invention.

In the drawings forming a part of thisdescriptijon: 'i j Fig. 1 is a side view of a masonry drill adapted to receive the starting tool; t

Fig. 2 is a separate side view of the starting tool;

Fig. 3 illustrates the starting tool inserted in a masonry drill;

Fig. 4 is an end View illustrating the starting tool inserted in a rotary drill;

Fig. 5 is a central longitudinal sectum taken through Fig. 3, showing the device in a masonry piercing operation;

Fig. 6 is an enlarged side end view of the starting tool;

Fig. '7 is an end view of the device shown in Fig. 6;

Fig. 8 is a partial side view of a modified form of the invention; While Fig. 9 is an end view of the device shown in Fig. 8.

For the drawings the numeral I0 refers to a cylindrical body having an axial bore Il, closed at the trailing end by an integral shank I2 portion adapted to be rotated on its longitudinal axis by a suitable motor. The distal end of the body I is enlarged forming an annular head I3 having teeth I5, disposed on the face I4 thereof, said teeth I5 being provided on one side with a shoulder portion Eea disposed approximately at right angles to the plane of the face I4, which preferably are four in number and are made of cemented carbide, or other suitable cutting materials and are positioned on the face Il! in such manner that cutting edges are approximately radial tc the head it, while their outer ends project outwardly from the periphery of the head I3 and their inner ends project into the bore Il.

A continuous spiral thread Il on the outer surface of the body lil, preferably square in cross section, provides means for carrying away masonry cuttings, and extends from a point near the head i3 to the proximal end of the body I0, while an annular groove I8, adjacent the head i3, permits the finely comminuted particles to pass from the outer ends of the teeth I5 to the spiral thread I?. The periphery of the head I3 may be flattened at I9, if desired, to form chanu nels in advance of teeth I5.

A slot 2i extending longitudinally of the body lil from where it intersects annular groove I8 to a point near the proximal end of the body lil, communicates with the bore EI and interrupts the thread Il, providing a passage supplementary to the slot 2l. for conducting granular material from the bore II to the thread Il along the major part of the latter. .A shallow longitudinal groove 2i.v extending in'v continuation of the slot 2| to the proximal end'of the body lil provides a passage supplementary to the slot 2I or to that passage provided by thread II, by which the drilled-out materia-1 reaches the area around the shank I2.

When the shank I2 is rotated, the teeth I5 are adapted to cut an annular channel in a masonry structure while the inner ends of the teeth I projecting into the bore I I, operate to grind up the core as it is formed. The projection of the outer ends of the teeth beyond the outer periphery of the head I3 causes the channel thus bored to be slightly oversize and thus prevents the bit from binding as it progresses inwardly.

Finely comminuted material, passes through the flattened portion IS of the head i3 to annular groove I8 and then to spiral thread i'I by which, it is moved from the hole. Particles dislodged at the face of the hole will enter the bore l I through the open end thereof between the inner ends of the teeth I5, to be subjected to the grinding action of the teeth I5, thus breaking up the core as it is formed, while slot ZI permits the material to be thrown by centrifugal force outwardlyT of the side of the bit at that part of the slot projecting from the hole. The slot 2i also permits immediate discharge to the thread Il of a part of the removed material suited in size for passage therealong. If the material is too large to enter the thread I'I, it is ground against the wall of hole until suitably comminuted. Material entering the thread Il is conveyed to the face of the masonry structure or, if the entire body of the bit has entered the hole, to the sone around the shank I2. The groove 22 at its points of intersection with the thread il provides sharp edges whereby any large particles traveling to the outer end of the bore be further comminuated.

The device heretofore described relates to a known type of drill currently being used. My starting tool, adapted to be used with the foregodrill, indicated by the numeral 23, comprises iank 255, having an integral head 25, while a pointed cutting member of suitable material such as tungsten carbide or the like, slopes rearwardly to side portions 2 terminating at the shank 2li. The rearwardly sloping sides of the cutting member 25 and side portions 22! constitute shoulders. If desired the cutting member 2 may be formed of the same material as the teeth I5 disposed on the face I4 of the head I3 of the body 5d. rThe starting tool above described is illustrated in Figs. 1 through 7 A modied form of my invention illustrated in Figs. 8 and 9 corresponds in a general way to the for; above described but differs therefrom in 'the provision of slots 28 disposed on the face I4 of the head I3, adapted to seat the rear ends of side portions 2'! of cutting member 26. If desired, the rear end of the side member 27 may be especially shaped and formed to lit into the slots My starting tool 23 is adapted to initiate a cutting or `piercing operation for the drill herein illustrated, the shank 24 thereof being inserted into the axial bore I I of the body I Il as illustrated in 3, 4 and 5, with the side members 2l of the cutting member 26 resting against and retained by the sides of the teeth I5. The body IEB is then caused to rotate on its longitudinal axis by means of an electric motor operatively connected to the shank i2'. thereof. The point of the cutting member 25 is pressed against the masonry at the point to be pierced, and continued rotation will advance the head 25 into the masonry until an opening has been cut corresponding in diameter to ap- 4 proximately the diameter of the face I4 of the head I3. The starting tool 23 is then lifted out of the axial bore I I of the drill body Ill and the drill is then operated as heretofore described, to drill a hole of desired size in the masonry.

When the starting tool is in vposition it will be noted that the head member 24, which is substantially cone-shaped, nts between and is centered by inner edges of the four teeth I5. Also, that, as the body member I0 is turned while urging the starting member into the masonry work, the side portions 2'I of the cutting member 25 are firmly forced against the shoulders I5a of the teeth I5. Thus, the starting tool is centered and retained without any additional securing means. It will also be seen that by so centering the cone-shaped head 25 by the teeth I5, which project somewhat into the bore II as above mentioned, a desirable clearance space between the head 25 and the entrance to the bore I I is provided.

The starting tool illustrated in Figs. 8 and 9 is secured to the face I4 of the head i3 by seating the side members 27 of the cutting member 2 in the slots 28, which provide satisfactory locking means for certain types of work.

It will be apparent to those skilled in the art that the invention disclosed herein, may be variously changed, used or modified, without departing from the spirit of the invention or sacrincing the advantages thereof, and that the embodiment of the invention herein is illustrative only, and that my invention is not limited thereto.

I. claim:

l. In a rotary bit for drilling concrete and the like, of the class including an elongated bored cylindrical body having a head at its leading end provided with a plurality of generally radially disposed cutting members including shoulder portions projecting from the face of said head, and cooperating means for carrying rearwardly and ejecting material out by said cutting members from the body, the combination with said bit of a starting bit comprising a shank portion, adapted to be inserted in the leading end of the cylindrical body bore, and a relatively flat pointed cutting member mounted on the leading end of said bit shank, projecting forwardly therefrom and provided with rearwardly outwardly sloping shoulders adapted to seat against the shoulder portions of the cutting members on the face of said cylindrical body upon rotation of said bit body.

2. In a rotary bit for drilling concrete and the like, of the class including an elongated bored cylindrical body having a head at its leading end provided with a plurality of generally radially disposed cutting members including shoulder portions projecting from the face of said head, and cooperating means for carrying rearwardly and ejecting material cut by said cutting members from the body, the combination with said bit of a starting bit comprising a shank portion, adapted to be inserted in the leading end of said bore, a head mounted on the leading end oi said bit shank, and generally radially disposed cutting members mounted on said head having a point at their leading end, and provided with shoulders projecting from said head and adapted to seat against the shoulder portions of the cutting members on the face at the leading end of said cylindrical body upon rotation of said body, for the purposes described.

3. In a rotary bit for drilling concrete and the like, of the class including lan elongated bored cylindrical body having a head at its leading end provided with a plurality of generally radially disposed cutting members including shoulder portions projecting from the face of said head, and cooperating means for carrying rearwardly and ejecting material cut by said cutting meinbers from the body, the combination with said bit of a starting bit, comprising a shank portion adapted to be inserte-d in the leading end of the cylindrical body bore, and a relatively flat pointed cutting member mounted on the leading end of said bit shank, projecting forwardly therefrom and provided with rearwardly outwardly sloping shoulders terminating in portions parallel to the axis of said bit shank, adapted 'to seat against the shoulder portions of the cutting mem-bers on the face of said cylindrical body 4. In a rotary bit for drilling concrete and the like, of the class including an elongated bored cylindrical body having a head at its leading end provided with a plurality of generally ra-dially disposed cutting members including shoulder portions projecting from the face of said head, and cooperating means for carrying rearwardly and ejecting material cut `by said cutting members from the body, the combination with said bit of a starting bit comprising a shank portion adapted to be inserted in the cylindrical body bore atV the lea-ding end thereof, and a cutting member, permanently mounted in a slot lat the leading end of said bit shank, said cutting member being relatively at and provided with a point at its leading end and rearwardly and outwardly sloping shoulders adapted to seat against the shoulder portions of the cutting members on the face of said cylindrical body.

5. In a rotary bit for drilling concrete and the like, of the class including an elongated bored cylindrical body having a head at its leading end provided with a, plurality of generally radially disposed cutting members including shoulder portions projecting from the face of lsaid head, and cooperating means for carrying rearwardly and ejecting material cut by said cutting meml bers from said body, the combination with said bit of a starting bit comprising a shank portion adapted to be inserted in the cylindrical body bore at the leading end thereof, and a cutting member, mounted on the leading end of said bit shank, said cutting member being relatively I'lat, embedded in said bit shank and provided with a point at its leading end and rearwardly and outwardly sloping shoulders terminating in shoulders parallel to the axis of said bit shank which are adapted to seat against the shoulder portions of the cutting members mounted on the face at the leading end of said cylindrical body.

WARREN M. BACON.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 527,814 Sauer Oct. 23, 1894 l 388,490 Suman Aug. 23, 1921 1,846,177 Bascom et al Feb. 23, 1932 1,990,341 Meyer Feb. 5, 1935 2,460,673 Berscheid Feb. 1, 1949 2,506,474 Tilden May 2, 1950 

